Embodiments of the present invention relate generally to a system for generating high voltage power in a fluid turbine.
Fluid turbines, such as wind turbines and marine hydrokinetic devices, generate electricity from kinetic energy of fluids such as wind and water that is transmitted to power grids for distribution. For example, a wind turbine typically includes a rotor component that converts the kinetic energy of the wind to mechanical energy and a synchronous generator that converts the mechanical energy to an alternating current (AC) power with varying frequency and a low voltage. The AC power generated by the synchronous generator is adjusted through a power conversion system before being transmitted to one ore more power grids for further distribution.
In one conventional power conversion system, the low voltage and varying frequency AC power is fed to an AC to DC converter disposed within the tower of the wind turbine via a low voltage cable. In a non-limiting example, the low voltage cable includes cables with an ability to transmit power having a voltage below 1000 volts. The AC to DC converter converts the varying frequency AC power to direct current (DC) power. The DC power is transmitted to an inverter via a DC link, and the inverter provides fixed frequency pulse width modulated AC power as an output. Furthermore, the fixed frequency pulse width modulated AC power is filtered to generate a sinusoidal fixed frequency AC power. The sinusoidal AC power is transferred to a step up transformer that converts the low voltage AC power to a high voltage AC power. Use of the inverters for pulse width modulation of the DC power in such embodiments may result in efficiency losses and further requires bulky and expensive filters to generate the sinusoidal AC power. Furthermore, the low voltage cables that are used to transfer low voltage AC power to the AC/DC converters are large, heavy, and expensive. In addition, the transformers are large and bulky. Furthermore, in embodiments wherein an offshore AC/DC converter is installed to collect the AC power from various wind turbines and convert the AC power to DC power suitable for long distance transmissions, extra costs are incurred.
Hence, there is a need for an improved and a less expensive system to address the aforementioned issues.